Glossary

A-B Line

A straight line, chosen by a machine operator and calculated by a guidance system. The A-B line defines a series of wheel tracks, a fixed distance apart, across the whole field.

Accuracy

In precision farming, the precision with which a system can locate a point at which data is recorded or the position of a vehicle. Different systems vary in their accuracy and their suitability for different tasks.

Active sensor

A device that generates emits its own light and measures the signal reflected from an object or surface. If used with GPS, these can be used to map different zones in crops.

Algorithm

A set of steps or rules for making calculations or solving problems, as used in computer programs.

Auto section control

A system that operates boom, planter of spreader sections automatically using a positioning system and precise on-off timing to minimize over application caused by overlapping or missed areas caused by underlapping. Automatic control can be used to control steering, headland management, spray boom height or rate of seed, fertiliser or agrichemicals.

Auto steering

A system based on GPS signals which steers a vehicle across a field without overlapping or underlapping. Autosteering is used on tractors, combines, forage harvesters and self propelled sprayers, spreaders and mowers.

Base station

A fixed site that sends and receives telecommunication signals.

Biomass map

A plan showing variation in crop canopy based on data from a biomass sensor. May indicate differences in soil characteristics which after agronomic field checking can be used to drive variable rate applications.

CANBUS

A digital wiring system that connects different control units in a vehicle (such as a tractor or combine) allowing data for machine control and diagnostics to be transferred between them. (CAN=Controller Area Network).

Controlled traffic farming (CTF)

A system that ensures that vehicles used in a field keep to the same permanent traffic lanes every year to restrict compaction of the soil to the smallest possible area.

Correction signal

A radio signal that improves the positioning accuracy of a basic GPS signal. Inaccuracies in the GPS signal are measured and correction data broadcast via satellite or ground system to the GPS receiver in a vehicle. See also RTK accuracy.

Crabbing

The tendency of a machine to slip sideways from its line of pull.

Crop reflectance

The amount of visible or invisible light reflected by a crop. Indices calculated from visible and near infrared spectra can be used to indicate biomass.

CTF

See controlled traffic farming.

Electrical conductivity

A measure of how easily an electrical current flows through a material such as soil. The conductivity may indicate the amount of salt, sand clay, organic matter, or water a soil contains. When associated with GPS data it can be used to create a soil map.

EC mapping

Characteristics of a soil may be differentiated by measuring its electrical conductivity. Can be deep or shallow sampling methods, with relationships between the two also potentially useful.

ECa Apparent electrical conductivity

Apparent electrical conductivity is influenced by: Moisture content, Salt content, Clay content, Bulk density. In each case a higher result in any of these factors results in a higher ECa.

Electromagnetic induction

A method of measuring the electrical conductivity of a soil by passing an electromagnetic wave through the ground.

EM38

An electromagnetic induction data collection type methodology applies when using Geonics instruments. EM38 measures ECa to a depth of 1-2m.

GAI

See green area index.

Geographic information System (GIS)

Software for capture and processing of data, associating it with a position in the field. Abbr. GIS

GLONASS

A satellite based navigation system owned by Russian Federation Government.

Global Positioning System (GPS)

A satellite based navigational system based on 24 satellites owned by the US department of defence.

GNSS Global Navigation Satellite Systems

Global Navigation Satellite Systems (e.g. GPS, GLONASS)

GPS compatible controller

A system to operate a sprayer, spreader or drill automatically according to an application map, using GPS.

Green Area Index (GAI)

A ratio of the total area of green plant tissue to the area of ground surrounding it.

Ground truthing

Observing and measuring something in the field to compare it with values calculated from an image obtained by remote sensing.

Guidance

A system based on a positioning system that shows a driver where to steer to cover a field at the spacing required for the implement being used without overlapping or underlapping, and to allow operating in the dark or when no useful reference points are available to assist accurate steering.

Hyperspectral imaging

The use of remote sensors to collect information about an object or area by building up an image based on hundreds to thousands of adjacent wavelength bands of the electromagnetic spectrum. Hyperspectral reflectance offers high resolution and may be used to help farmers assess the development, health and nutrient status of crops.

Infrared sensor

A device that can collect information about a field, soil or crop from a distance by measuring the amount of infrared light reflected from it.

ISOBUS

International standard for communication between tractors and implements, allows operation of different implements through one control terminal in the tractor.

Kriging

A statistical technique which allows calculation of unknown values from known values. This allows prediction of a value at a point based on values at nearby points. It may also be used to smooth errors in data.

LIDAR

A system which works by measuring reflected laser beams to accurately map the earth’s surface and vegetation. A LIDAR topography laser measures distance to points, and allows for calculations of mean height and creation of maps. (LIDAR= Light Detection and Ranging)

Management Zone

A part of a field, identified by analysis of a yield map or soil map, that is defined by a specific characteristic such as soil type, fertility or weed cover and may be managed in an appropriate way.

Nanosensor

A highly sensitive sensor based on nanotechnology, designed to perform precise functions such as measuring individual proteins or triggering electrical chemical or enzymatic reactions in response to changing environmental conditions.

NDVI

Normalised difference vegetation index, based on the relationship between visible light reflectance and near infrared reflectance of a crop canopy. Can be used to assess size, nutrient status and health.

Passive sensor

A light sensor which captures data in daytime, by measuring the amount of light reflected from the crop (for visible wavelengths) or absorbed and re-emitted (for thermal, infrared wavelengths). Passive light sensors are affected by the angle of the sun and cloud cover, although some can correct for changes.

Precision Agriculture

Management of farming practices that uses technology such as GPS, computers and remote sensing devices to provide information on which enhanced farming decisions can be made.

Remote sensing

The process of detecting information about a field, soil or crop from a distance, using sensors mounted on satellites, aircraft, tractors etc.

RTK (Real Time Kinematic)

A system that uses a fixed ground station to measure satellite drift accurately and send a correction signal by radio, directly to GPS equipped vehicles. Because it is not affected by the atmospheric conditions which affect satellite signals, RTK correction provides high and repeatable accuracy of 1-2cm).

Strip tillage

Strip tillage involves cultivating narrow planting strips while leaving much of the paddock uncultivated. Generally, less than half the soil is cultivated under a strip-till system. The cultivated strip creates optimum tilth and allows conventional planters to be used to sow the crop, and helps ensure even germination. The uncultivated ground prevents wind erosion and maintains the soil strength and ability to support traffic.

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